The calculated distance (air line) between Monheim am Rhein and Rommerskirchen is approximately 10 miles respectively 16 kilometers.
By car or train, the actual journey to Rommerskirchen is certainly longer, as only the direct route (as the crow flies) between Monheim am Rhein and Rommerskirchen has been calculated here.
Air line (approximately)
16 kilometers
9 nautical miles